1. Field of the Invention
The present invention relates to a method and a device for manufacturing an imaging module having an optical image stabilizing function.
2. Description of the Related Art
As is well known in recent years, some of imaging modules installed in electronic devices, such as mobile phones, smartphones, or tablet computers, have an optical image stabilizer (OIS) function (see Japanese Unexamined Patent Application Publication No. JP2012-256017A).
An OIS mechanism disclosed in Japanese Unexamined Patent Application Publication No. JP2012-256017A employs a so-called suspension support structure. The optical image stabilizer (OIS) mechanism has a structure in which a movable image-stabilizing unit (imaging unit) is supported at four corners using four suspension wires and the movable image-stabilizing unit is driven in two-axis directions perpendicular to the optical axis for image stabilization. A mechanism for driving the movable image-stabilizing unit includes magnets, disposed on four outer-peripheral side surfaces of a cover portion on which the movable image-stabilizing unit is mounted, and a coil, disposed on a fixed-body-side yoke so as to oppose the magnets. This driving mechanism allows the movable image-stabilizing unit to be driven for image stabilization independently of two axes perpendicular to the optical axis.
An imaging module is manufactured as a result of fixing a lens unit including such an OIS mechanism (including a movable image-stabilizing unit and suspension wires) and a lens group to an imaging device unit including an imaging device. When the lens unit and the imaging device unit are fixed to each other, a so-called one-sided blurring problem, which renders a portion of an image out of focus, occurs unless the position of the lens group relative to the imaging device is accurately set. Thus, a method is provided for fixing a lens unit to an imaging device unit in the state where a lens group is adjusted to be in a predetermined reference position using a jig disclosed in, for example, Japanese Unexamined Patent Application Publication No. JP2012-256017A.
Japanese Unexamined Patent Application Publication No. JP2010-021985A discloses the following method for manufacturing an imaging module. In the method, an imaging device unit and a lens unit are set on an axis perpendicular to a measurement chart. The relative position of the imaging device unit, the lens unit, and the measurement chart on the axis is changed. A reference position of a lens group is calculated on the basis of results obtained after an imaging device captures an image of the measurement chart at each relative position. The imaging device unit and the lens unit are fixed to each other in the state where the tilts and the positions of the imaging device unit and the lens unit have been adjusted on the basis of these results.
An imaging module having an OIS mechanism of a suspension support structure is affected by a magnetic field produced by an electronic device on which this imaging module is mounted. FIG. 27 is a cross-sectional view of a main portion of a smartphone 2 when an imaging module 1 is mounted on the smartphone 2. As illustrated in this drawing, a speaker 3 is disposed near the imaging module 1. Thus, the imaging module 1 is affected by a magnetic force generated by the speaker 3, thereby resulting in a problem of tilting of the lens group from the reference position.
Japanese Unexamined Patent Application Publication No. JP2009-071495A describes that when a speaker, which is a magnetic-field generating unit, has a magnetic force of 100 gausses and an imaging module is spaced apart from the speaker by 10 mm or longer, a reliable operation of the imaging module is ensured.
As in the case of the invention described in Japanese Unexamined Patent Application Publication No. JP2009-071495A, an imaging module is usually disposed in an electronic device so as to be spaced a distance apart from a magnetic-field generating unit. However, because of reasons such as the design or space of the electronic device, in some cases, the imaging module has to be disposed near the magnetic-field generating unit in the electronic device. In such cases, the movable image-stabilizing unit is tilted by being affected by the magnetic field produced by the magnetic-field generating unit. This causes a problem of tilting of the lens group in the movable image-stabilizing unit from the reference position.